In 173 patients free of bronchiolitis obliterans syndrome at least 6 months post-transplant, having 10 or more colony-forming units of mesenchymal cells in bronchoalveolar lavage fluid carried a >5.0 hazard ratio for subsequently developing BOS. The relation persisted after multivariate analysis, report Badri et al. AJRCCM 2011;183:1062-1070.